The commercial production of cookies generally are prepared from sugar, flour, fat or shortening leavening and optional flavors. The ingredients are combined and blended in a suitable blending apparatus in a batch fashion. After the dough is formed, additives such as nuts or chocolate pieces are admixed to uniformly distribute the particles throughout the dough. The dough is then transferred to a suitable shaping and forming apparatus to form the dough pieces. The mixing of the particles must be under low shear conditions to prevent the destruction of the structural integrity of the particles. The integrity of the particles will influence the flavor and the texture of the final product and may inhibit the consumer acceptance of the product.
Processes have been proposed to improve the consumer acceptance of a product by applying the edible particles to the surface of the product during different stages of the formation of the dough piece. Securing the particles to the surface dough has shown to be difficult either before or after baking. During the baking, cooling and packaging stages of the cookie production, large quantities of the edible pieces become dislodged resulting in a product that is unsatisfactory to the consumer. In addition, the edible particle processing stage and loss of the edible particles from the product increase the final manufacturing costs.
In the production of a high oil containing farinaceous composition by extrusion cooking, mobility and immiscibility of the water and oil phases generally increase with increasing temperature. Additionally, the mechanical action of extruder screws tends to increase separation of oil from the remaining cookie mass. The tendency for the oil to separate is at locations within the extruder at which the components are subjected to the highest pressure. Exemplary of high pressure locations in a twin screw extruder are: 1) the space between the extruder screw tips and the die orifice, and 2) the narrowest or more restricted passageways between the left and right hand screw elements.
Oil separation under system pressure (screw or die pressure) can be manifested in extruder surging or uneven mass flow rates from the die. Upon extrusion from the die, separated oil may: 1) appear as a coating on the remaining dough mass, or 2) periodically discharge separately from the remaining dough mass. Non-homogeneous dough production and discontinuous extruder operation may thus result from oil separation. The problem of oil separation increases with increasing oil levels.
Water separation from flour, up to the boiling point of water, is generally not a problem because of the more hydrophilic properties of flour components such as gluten and starch. As flour and water temperatures are raised, increased migration of water into starch granules, protein (e.g. gluten) denaturization, and starch gelatinization tend to occur. The binding or reaction of water with flour components may promote separation of oil: a) by making the flour components more polar or hydrophilic and b) by creating a greater mass of hydrophilic components.
Conventional cookie production involves forming cookie dough preforms or pieces followed by baking of the pieces. Low temperatures, typically at about room temperature, are used to form the dough. The low temperature mixing generally avoids separation of shortening or fat from hydrophilic dough components. While baking temperatures in a conventional oven, such as a band oven, may promote oil separation, there is no mixing or pressing action performed at the baking temperatures. Any oil separation which may occur in such ovens does not generally interfere with continuous operability of the cookie production process as it would in a continuous cooker/extruder process.
In addition to high temperature mixing and high system pressure, the presence of sugar in a cookie dough may also increase oil and water separation. Solubilization of sugars in water increases the relative amount of the hydrophilic mass. This in turn may tend to promote oil separation.
The elimination or significant reduction of added water or a source of added water in a cooker extruder tends to reduce oil separation from hydrophilic cookie dough components at elevated temperatures. However, added water or a source of water is needed in cookie production for formability or machinability of cookie doughs into sheets or pieces at high production rates. Water also helps to disperse cookie ingredients and to promote flavor and color development.
Cooking of dough products at elevated temperatures changes the texture and the flavor of the dough. The temperatures experienced in the baking oven and in a cooker-extruder will develop many of the desirable flavors. However, the cooking temperatures will inherently destroy some of the desirable compositions in the food product. A number of additives are commonly added to dough products to improve the shelf-stability, color, and flavor of the dough product. Typically these additives are combined during the mixing stage of the dough and subjected to the high cooking temperatures. The high temperatures often result in a loss of the activity of the additive. Many flavoring compositions contain volatile compounds which dissipate during baking. Some antioxidants and vitamins may be destroyed during the heating step. The intense heating experienced in a cooker-extruder have limited the use of extruders to compositions that are relatively heat stable. Alternative extrusion cooking methods rely on the short residence time in the extruder or lower the barrel temperature to avoid decomposition.
Efforts to overcome the loss of activity of these compounds usually result in adding excessive amounts of the compound during mixing or, alternatively, applying a coating of the compound over the finished product. These efforts have experienced only limited success in obtaining satisfactory concentrations. For example, many of the concentrated coatings tend to impart a bitter flavor to the food. Applying a coating of the compound does not sufficiently penetrate the interior of the product and produces a high concentration on the surface and low concentration toward the center. In addition, a carrier is often times necessary to apply the compound and further tends to dilute the concentration. When an aqueous solution is sprayed onto the food product, the water must typically be removed to avoid an unacceptable moisture level on the surface. The coating compositions are further exposed to the atmosphere and to sunlight which may degrade or alter their activity over time. In the case of preservatives and antioxidants, it is preferable to have the compounds remain in the active form for an extended period of time to prevent spoilage of the food product. Coating compositions of preservatives generally have a high initial activity, which decreases steadily as the product ages.
Prior extrusion cooking methods have further not been able to admix large particulates into the composition. The intense mixing experiences in the typical extruder is under high shear which destroys the structural integrity of the particle. If the extruder is designed to avoid the destruction of the particles, proper mixing and cooking may not occur. Products intending to have large edible particles are generally prepared by extruding a substrate dough followed by a deposited layer of the particles and a superimposed dough layer to cover the particles.
There is, therefore, a need for a cooked cookie having heat labile additives uniformly dispersed throughout the cookie structure that has not been subjected to the destructive baking temperatures and high extruder pressures. The prior methods typically mix the cookie dough ingredients in the uncooked state and then form a dough into dough pieces for subsequent baking. The high baking temperatures generally destroy or deactivate many of the added compositions. Conventional extrusion cooking also subjects the additives to the deactivation temperatures.
The present invention is directed to a continuous method of preparing a cookie having heat or shear sensitive stabilized additives. Specifically, the invention relates to the extrusion heating of a high fat content cookie composition where the cookie composition is subjected to the high temperatures before the heat or shear sensitive additives are combined with the cookie composition. The cookie composition of the present invention is extruded under low pressure and baked to brown the surface of the cookie, cause the dough to rise and develop the crumb-like structure.